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Monte Carlo simulations of particle acceleration at oblique shocksThe Fermi shock acceleration mechanism may be responsible for the production of high-energy cosmic rays in a wide variety of environments. Modeling of this phenomenon has largely focused on plane-parallel shocks, and one of the most promising techniques for its study is the Monte Carlo simulation of particle transport in shocked fluid flows. One of the principal problems in shock acceleration theory is the mechanism and efficiency of injection of particles from the thermal gas into the accelerated population. The Monte Carlo technique is ideally suited to addressing the injection problem directly, and previous applications of it to the quasi-parallel Earth bow shock led to very successful modeling of proton and heavy ion spectra, as well as other observed quantities. Recently this technique has been extended to oblique shock geometries, in which the upstream magnetic field makes a significant angle Theta(sub B1) to the shock normal. Spectral resutls from test particle Monte Carlo simulations of cosmic-ray acceleration at oblique, nonrelativistic shocks are presented. The results show that low Mach number shocks have injection efficiencies that are relatively insensitive to (though not independent of) the shock obliquity, but that there is a dramatic drop in efficiency for shocks of Mach number 30 or more as the obliquity increases above 15 deg. Cosmic-ray distributions just upstream of the shock reveal prominent bumps at energies below the thermal peak; these disappear far upstream but might be observable features close to astrophysical shocks.
Document ID
19950035958
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Baring, Matthew G.
(NASA Goddard Space Flight Center Greenbelt, MD, US, United States)
Ellison, Donald C.
(North Carolina State Univ. Raleigh, NC, US, United States)
Jones, Frank C.
(NASA Goddard Space Flight Center Greenbelt, MD, US, United States)
Date Acquired
August 16, 2013
Publication Date
February 1, 1994
Publication Information
Publication: Astrophysical Journal Supplement Series
Volume: 90
Issue: 2
ISSN: 0067-0049
Subject Category
Astrophysics
Accession Number
95A67557
Distribution Limits
Public
Copyright
Other

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